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<html>
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
    <title>Three.js - Custom BufferGeometry - Indexed</title>
    <style>
    html, body {
        height: 100%;
        margin: 0;
    }
    #c {
        width: 100%;
        height: 100%;
        display: block;
    }
    </style>
  </head>
  <body>
    <canvas id="c"></canvas>
  </body>
<script type="importmap">
{
  "imports": {
    "three": "../../build/three.module.js"
  }
}
</script>

<script type="module">
import * as THREE from 'three';

function main() {

	const canvas = document.querySelector( '#c' );
	const renderer = new THREE.WebGLRenderer( { antialias: true, canvas } );

	const fov = 75;
	const aspect = 2; // the canvas default
	const near = 0.1;
	const far = 100;
	const camera = new THREE.PerspectiveCamera( fov, aspect, near, far );
	camera.position.z = 5;

	const scene = new THREE.Scene();

	{

		const color = 0xFFFFFF;
		const intensity = 3;
		const light = new THREE.DirectionalLight( color, intensity );
		light.position.set( - 1, 2, 4 );
		scene.add( light );

	}

	// NOT A GOOD EXAMPLE OF HOW TO MAKE A CUBE!
	// Only trying to make it clear most vertices are unique
	const vertices = [
		// front
		{ pos: [ - 1, - 1, 1 ], norm: [ 0, 0, 1 ], uv: [ 0, 0 ], }, // 0
		{ pos: [ 1, - 1, 1 ], norm: [ 0, 0, 1 ], uv: [ 1, 0 ], }, // 1
		{ pos: [ - 1, 1, 1 ], norm: [ 0, 0, 1 ], uv: [ 0, 1 ], }, // 2
		{ pos: [ 1, 1, 1 ], norm: [ 0, 0, 1 ], uv: [ 1, 1 ], }, // 3
		// right
		{ pos: [ 1, - 1, 1 ], norm: [ 1, 0, 0 ], uv: [ 0, 0 ], }, // 4
		{ pos: [ 1, - 1, - 1 ], norm: [ 1, 0, 0 ], uv: [ 1, 0 ], }, // 5
		{ pos: [ 1, 1, 1 ], norm: [ 1, 0, 0 ], uv: [ 0, 1 ], }, // 6
		{ pos: [ 1, 1, - 1 ], norm: [ 1, 0, 0 ], uv: [ 1, 1 ], }, // 7
		// back
		{ pos: [ 1, - 1, - 1 ], norm: [ 0, 0, - 1 ], uv: [ 0, 0 ], }, // 8
		{ pos: [ - 1, - 1, - 1 ], norm: [ 0, 0, - 1 ], uv: [ 1, 0 ], }, // 9
		{ pos: [ 1, 1, - 1 ], norm: [ 0, 0, - 1 ], uv: [ 0, 1 ], }, // 10
		{ pos: [ - 1, 1, - 1 ], norm: [ 0, 0, - 1 ], uv: [ 1, 1 ], }, // 11
		// left
		{ pos: [ - 1, - 1, - 1 ], norm: [ - 1, 0, 0 ], uv: [ 0, 0 ], }, // 12
		{ pos: [ - 1, - 1, 1 ], norm: [ - 1, 0, 0 ], uv: [ 1, 0 ], }, // 13
		{ pos: [ - 1, 1, - 1 ], norm: [ - 1, 0, 0 ], uv: [ 0, 1 ], }, // 14
		{ pos: [ - 1, 1, 1 ], norm: [ - 1, 0, 0 ], uv: [ 1, 1 ], }, // 15
		// top
		{ pos: [ 1, 1, - 1 ], norm: [ 0, 1, 0 ], uv: [ 0, 0 ], }, // 16
		{ pos: [ - 1, 1, - 1 ], norm: [ 0, 1, 0 ], uv: [ 1, 0 ], }, // 17
		{ pos: [ 1, 1, 1 ], norm: [ 0, 1, 0 ], uv: [ 0, 1 ], }, // 18
		{ pos: [ - 1, 1, 1 ], norm: [ 0, 1, 0 ], uv: [ 1, 1 ], }, // 19
		// bottom
		{ pos: [ 1, - 1, 1 ], norm: [ 0, - 1, 0 ], uv: [ 0, 0 ], }, // 20
		{ pos: [ - 1, - 1, 1 ], norm: [ 0, - 1, 0 ], uv: [ 1, 0 ], }, // 21
		{ pos: [ 1, - 1, - 1 ], norm: [ 0, - 1, 0 ], uv: [ 0, 1 ], }, // 22
		{ pos: [ - 1, - 1, - 1 ], norm: [ 0, - 1, 0 ], uv: [ 1, 1 ], }, // 23
	];
	const positions = [];
	const normals = [];
	const uvs = [];
	for ( const vertex of vertices ) {

		positions.push( ...vertex.pos );
		normals.push( ...vertex.norm );
		uvs.push( ...vertex.uv );

	}

	const geometry = new THREE.BufferGeometry();
	const positionNumComponents = 3;
	const normalNumComponents = 3;
	const uvNumComponents = 2;
	geometry.setAttribute(
		'position',
		new THREE.BufferAttribute( new Float32Array( positions ), positionNumComponents ) );
	geometry.setAttribute(
		'normal',
		new THREE.BufferAttribute( new Float32Array( normals ), normalNumComponents ) );
	geometry.setAttribute(
		'uv',
		new THREE.BufferAttribute( new Float32Array( uvs ), uvNumComponents ) );

	geometry.setIndex( [
		0, 1, 2, 2, 1, 3,
		4, 5, 6, 6, 5, 7,
		8, 9, 10, 10, 9, 11,
		12, 13, 14, 14, 13, 15,
		16, 17, 18, 18, 17, 19,
		20, 21, 22, 22, 21, 23,
	] );

	const loader = new THREE.TextureLoader();
	const texture = loader.load( 'resources/images/star.png' );
	texture.colorSpace = THREE.SRGBColorSpace;

	function makeInstance( geometry, color, x ) {

		const material = new THREE.MeshPhongMaterial( { color, map: texture } );

		const cube = new THREE.Mesh( geometry, material );
		scene.add( cube );

		cube.position.x = x;
		return cube;

	}

	const cubes = [
		makeInstance( geometry, 0x88FF88, 0 ),
		makeInstance( geometry, 0x8888FF, - 4 ),
		makeInstance( geometry, 0xFF8888, 4 ),
	];

	function resizeRendererToDisplaySize( renderer ) {

		const canvas = renderer.domElement;
		const width = canvas.clientWidth;
		const height = canvas.clientHeight;
		const needResize = canvas.width !== width || canvas.height !== height;
		if ( needResize ) {

			renderer.setSize( width, height, false );

		}

		return needResize;

	}

	function render( time ) {

		time *= 0.001;

		if ( resizeRendererToDisplaySize( renderer ) ) {

			const canvas = renderer.domElement;
			camera.aspect = canvas.clientWidth / canvas.clientHeight;
			camera.updateProjectionMatrix();

		}

		cubes.forEach( ( cube, ndx ) => {

			const speed = 1 + ndx * .1;
			const rot = time * speed;
			cube.rotation.x = rot;
			cube.rotation.y = rot;

		} );

		renderer.render( scene, camera );

		requestAnimationFrame( render );

	}

	requestAnimationFrame( render );

}

main();
</script>
</html>
